module Poro
  module Util
    module Inflector
      # A singleton instance of this class is yielded by Inflector.inflections, which can then be used to specify additional
      # inflection rules. Examples:
      #
      #   ActiveSupport::Inflector.inflections do |inflect|
      #     inflect.plural /^(ox)$/i, '\1\2en'
      #     inflect.singular /^(ox)en/i, '\1'
      #
      #     inflect.irregular 'octopus', 'octopi'
      #
      #     inflect.uncountable "equipment"
      #   end
      #
      # New rules are added at the top. So in the example above, the irregular rule for octopus will now be the first of the
      # pluralization and singularization rules that is runs. This guarantees that your rules run before any of the rules that may
      # already have been loaded.
      class Inflections
        def self.instance
          @__instance__ ||= new
        end

        attr_reader :plurals, :singulars, :uncountables, :humans

        def initialize
          @plurals, @singulars, @uncountables, @humans = [], [], [], []
        end

        # Specifies a new pluralization rule and its replacement. The rule can either be a string or a regular expression.
        # The replacement should always be a string that may include references to the matched data from the rule.
        def plural(rule, replacement)
          @uncountables.delete(rule) if rule.is_a?(String)
          @uncountables.delete(replacement)
          @plurals.insert(0, [rule, replacement])
        end

        # Specifies a new singularization rule and its replacement. The rule can either be a string or a regular expression.
        # The replacement should always be a string that may include references to the matched data from the rule.
        def singular(rule, replacement)
          @uncountables.delete(rule) if rule.is_a?(String)
          @uncountables.delete(replacement)
          @singulars.insert(0, [rule, replacement])
        end

        # Specifies a new irregular that applies to both pluralization and singularization at the same time. This can only be used
        # for strings, not regular expressions. You simply pass the irregular in singular and plural form.
        #
        # Examples:
        #   irregular 'octopus', 'octopi'
        #   irregular 'person', 'people'
        def irregular(singular, plural)
          @uncountables.delete(singular)
          @uncountables.delete(plural)
          if singular[0,1].upcase == plural[0,1].upcase
            plural(Regexp.new("(#{singular[0,1]})#{singular[1..-1]}$", "i"), '\1' + plural[1..-1])
            plural(Regexp.new("(#{plural[0,1]})#{plural[1..-1]}$", "i"), '\1' + plural[1..-1])
            singular(Regexp.new("(#{plural[0,1]})#{plural[1..-1]}$", "i"), '\1' + singular[1..-1])
          else
            plural(Regexp.new("#{singular[0,1].upcase}(?i)#{singular[1..-1]}$"), plural[0,1].upcase + plural[1..-1])
            plural(Regexp.new("#{singular[0,1].downcase}(?i)#{singular[1..-1]}$"), plural[0,1].downcase + plural[1..-1])
            plural(Regexp.new("#{plural[0,1].upcase}(?i)#{plural[1..-1]}$"), plural[0,1].upcase + plural[1..-1])
            plural(Regexp.new("#{plural[0,1].downcase}(?i)#{plural[1..-1]}$"), plural[0,1].downcase + plural[1..-1])
            singular(Regexp.new("#{plural[0,1].upcase}(?i)#{plural[1..-1]}$"), singular[0,1].upcase + singular[1..-1])
            singular(Regexp.new("#{plural[0,1].downcase}(?i)#{plural[1..-1]}$"), singular[0,1].downcase + singular[1..-1])
          end
        end

        # Add uncountable words that shouldn't be attempted inflected.
        #
        # Examples:
        #   uncountable "money"
        #   uncountable "money", "information"
        #   uncountable %w( money information rice )
        def uncountable(*words)
          (@uncountables << words).flatten!
        end

        # Specifies a humanized form of a string by a regular expression rule or by a string mapping.
        # When using a regular expression based replacement, the normal humanize formatting is called after the replacement.
        # When a string is used, the human form should be specified as desired (example: 'The name', not 'the_name')
        #
        # Examples:
        #   human /_cnt$/i, '\1_count'
        #   human "legacy_col_person_name", "Name"
        def human(rule, replacement)
          @humans.insert(0, [rule, replacement])
        end

        # Clears the loaded inflections within a given scope (default is <tt>:all</tt>).
        # Give the scope as a symbol of the inflection type, the options are: <tt>:plurals</tt>,
        # <tt>:singulars</tt>, <tt>:uncountables</tt>, <tt>:humans</tt>.
        #
        # Examples:
        #   clear :all
        #   clear :plurals
        def clear(scope = :all)
          case scope
            when :all
              @plurals, @singulars, @uncountables = [], [], []
            else
              instance_variable_set "@#{scope}", []
          end
        end
      end

      # Yields a singleton instance of Inflector::Inflections so you can specify additional
      # inflector rules.
      #
      # Example:
      #   ActiveSupport::Inflector.inflections do |inflect|
      #     inflect.uncountable "rails"
      #   end
      def inflections
        if block_given?
          yield Inflections.instance
        else
          Inflections.instance
        end
      end

      # Returns the plural form of the word in the string.
      #
      # Examples:
      #   "post".pluralize             # => "posts"
      #   "octopus".pluralize          # => "octopi"
      #   "sheep".pluralize            # => "sheep"
      #   "words".pluralize            # => "words"
      #   "CamelOctopus".pluralize     # => "CamelOctopi"
      def pluralize(word)
        result = word.to_s.dup

        if word.empty? || inflections.uncountables.include?(result.downcase)
          result
        else
          inflections.plurals.each { |(rule, replacement)| break if result.gsub!(rule, replacement) }
          result
        end
      end

      # The reverse of +pluralize+, returns the singular form of a word in a string.
      #
      # Examples:
      #   "posts".singularize            # => "post"
      #   "octopi".singularize           # => "octopus"
      #   "sheep".singularize            # => "sheep"
      #   "word".singularize             # => "word"
      #   "CamelOctopi".singularize      # => "CamelOctopus"
      def singularize(word)
        result = word.to_s.dup

        if inflections.uncountables.any? { |inflection| result =~ /#{inflection}\Z/i }
          result
        else
          inflections.singulars.each { |(rule, replacement)| break if result.gsub!(rule, replacement) }
          result
        end
      end

      # Capitalizes the first word and turns underscores into spaces and strips a
      # trailing "_id", if any. Like +titleize+, this is meant for creating pretty output.
      #
      # Examples:
      #   "employee_salary" # => "Employee salary"
      #   "author_id"       # => "Author"
      def humanize(lower_case_and_underscored_word)
        result = lower_case_and_underscored_word.to_s.dup

        inflections.humans.each { |(rule, replacement)| break if result.gsub!(rule, replacement) }
        result.gsub(/_id$/, "").gsub(/_/, " ").capitalize
      end

      # Capitalizes all the words and replaces some characters in the string to create
      # a nicer looking title. +titleize+ is meant for creating pretty output. It is not
      # used in the Rails internals.
      #
      # +titleize+ is also aliased as as +titlecase+.
      #
      # Examples:
      #   "man from the boondocks".titleize # => "Man From The Boondocks"
      #   "x-men: the last stand".titleize  # => "X Men: The Last Stand"
      def titleize(word)
        humanize(underscore(word)).gsub(/\b('?[a-z])/) { $1.capitalize }
      end

      # Create the name of a table like Rails does for models to table names. This method
      # uses the +pluralize+ method on the last word in the string.
      #
      # Examples
      #   "RawScaledScorer".tableize # => "raw_scaled_scorers"
      #   "egg_and_ham".tableize     # => "egg_and_hams"
      #   "fancyCategory".tableize   # => "fancy_categories"
      def tableize(class_name)
        pluralize(underscore(class_name))
      end

      # Create a class name from a plural table name like Rails does for table names to models.
      # Note that this returns a string and not a Class. (To convert to an actual class
      # follow +classify+ with +constantize+.)
      #
      # Examples:
      #   "egg_and_hams".classify # => "EggAndHam"
      #   "posts".classify        # => "Post"
      #
      # Singular names are not handled correctly:
      #   "business".classify     # => "Busines"
      def classify(table_name)
        # strip out any leading schema name
        camelize(singularize(table_name.to_s.sub(/.*\./, '')))
      end
    end
  end
end